(Adds details on Iowa Right to Life Committee challenge, background on aggregate donation limits)

By Lawrence Hurley

WASHINGTON, April 7 (Reuters) - Ducking a new case on the divisive issue of campaign finance, the U.S. Supreme Court on Monday rejected a challenge to an Iowa law that bans corporate contributions in state elections.

The court declined to take up the case just days after it issued a ruling lifting limits on the aggregate amount individual donors can give in federal elections.

By opting not to hear the case, the court left intact an 8th U.S. Circuit Court of Appeals ruling from June 2013 that upheld the ban. By so doing, the court indicated it was unwilling for now to press ahead with further deregulation of campaign finance following the 5-4 ruling on Wednesday in the case of McCutcheon v. Federal Election Commission.

Iowa Right to Life Committee Inc, an anti-abortion group, challenged the ban, saying it violated the free speech and equal protection of the law provisions of the U.S. Constitution. The group sued after Iowa revised its laws in light of the 2010 Supreme Court ruling Citizens United v. Federal Election Commission, in which the court said corporations and unions could make unlimited independent expenditures that are not coordinated with a campaign.

The Iowa law was changed to allow for independent expenditures by corporations and unions but the ban on direct contributions to candidates and committees by corporations was left intact. Unions can make such contributions.

In the McCutcheon case, the conservative majority of the court eliminated the aggregate donation limits of $48,600 to candidates and $74,600 to state and local political party committees during each two-year election cycle.

The court also embraced a narrow definition of the kind of corruption that could be prompted by donations, which could make it harder for campaign finance laws to withstand legal challenges.

The case is Iowa Right to Life Committee v. Tooker, U.S. Supreme Court, 13-407. (Reporting by Lawrence Hurley; Editing by Howard Goller and Meredith Mazzilli)